Device for controlling additive manufacturing machinery

ABSTRACT

A computing device for controlling the operation of an additive manufacturing machine comprises a memory element and a processing element. The memory element is configured to store a three-dimensional model of a part to be manufactured, wherein the three-dimensional model defines a plurality of cross sections of the part. The processing element is in communication with the memory element. The processing element is configured to receive the three-dimensional model, determine a path across a surface of each cross section, wherein the path includes a plurality of parallel lines, calculate a power for a radiation beam to scan each of the lines, such that the power varies from line to line non-linearly according to a length of the line, and calculate a scan speed for the radiation beam for each of the lines, such that the scan speed varies line to line non-linearly according to the power of the radiation beam.

RELATED APPLICATION

The current patent application is a continuation patent applicationwhich claims priority benefit, with regard to all common subject matter,to U.S. patent application Ser. No. 15/250,562, entitled “DEVICE FORCONTROLLING ADDITIVE MANUFACTURING MACHINERY”, and filed Aug. 29, 2016.The earlier-filed patent application is hereby incorporated by referencein its entirety into the current application.

STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with Government support under Contract No.:DE-NA0002839 awarded by the United States Department of Energy/NationalNuclear Security Administration. The Government has certain rights inthe invention.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the current invention relate to devices for controllingthe operation of additive manufacturing machinery.

Description of the Related Art

Additive manufacturing machinery creates parts using processes that addmaterial in successive steps to form the part as opposed to traditional,subtractive processes that start with a block of raw material and thenremove a portion of the material, such as by machining, to form thefinal part. An additive manufacturing machine may also be referred to asa 3D printer. An example of an additive manufacturing machine is anelectron beam melt (EBM) machine. The EBM machine may include a rawmaterial bed, an electron beam generator, and a controller. The rawmaterial bed may be a square or rectangular plate that retains rawmaterial and is held in a vertical shaft. Typically, the raw material isa powdered metal or metal alloy. The electron beam generator may bepositioned above the raw material bed and may generate an electron beamonto the raw material in the bed. The electron beam possesses sufficientpower to melt particles of the raw material and fuse them together. Thecontroller generally controls the power and the relative motion of theelectron beam.

The EBM machine may operate as follows. A three-dimensional computermodel of the part may be created. The model includes coordinates of thematerial boundaries or surface area dimensions for each of a pluralityof thin, parallel, planar cross sections of the part. The model may beloaded into the controller for the electron beam generator. A firstlayer of raw material may be deposited onto the raw material bed by amaterial dispenser or hopper. The electron beam may be guided to scan apath to melt and fuse the raw material that lies within the boundariesof the first cross section of the part. Typically, the path includes aserpentine pattern of spaced-apart parallel lines. After all of the rawmaterial that forms the first cross section of the part has been meltedand fused, the raw material bed lowers in the shaft by a distance equalto one cross-sectional thickness. A second layer of raw material isdeposited into the bed on top of the first layer. The electron beam maybe guided in a path to melt and fuse the raw material that lies withinthe boundaries of the second cross section of the part. Once fusing andmelting is complete, the raw material bed lowers in the shaft andanother layer of raw material is added on top of the previous layer. Theprocess continues until all cross sections of the part have been formed.The part is complete when excess raw material has been removed.

The quality of the completed part relies, to a certain extent, on properheating and cooling of the material along adjacent path lines of theelectron beam. As the beam moves along one path line, it will heat thematerial along adjacent path lines. If the material that has alreadybeen melted at a point along a previously-scanned path line cools toomuch before the electron beam arrives at the same point on thecurrently-scanned, adjacent path line, then defects, such as highsurface porosity and microcracks, may occur. The heating and coolingbehavior of the raw material may result from the intrinsic thermalconductivity properties of the metals and alloys used. Some raw materialmetals, such as aluminum, copper, gold, silver, and their alloys, have ahigher thermal conductivity than other metals, such as carbon steel. Themetals and alloys with higher thermal conductivity will cool morerapidly than those with lower thermal conductivity. In addition, areasof a cross section of the part with longer path lines may experience alonger time from when the electron beam leaves a given point on apreviously-scanned path line until the beam intersects the same point onthe currently-scanned, adjacent path line. During the longer time, thematerial at the given point could cool to an undesirable level before itis heated up again. These issues prevent current additive manufacturingmachinery from producing high quality parts from a variety of metals.

SUMMARY OF THE INVENTION

Embodiments of the current invention solve the above-mentioned problemsand provide a distinct advance in the art of control of additivemanufacturing machinery. More particularly, embodiments of the inventionprovide computing devices for controlling additive manufacturingmachinery that compensate for variations in raw material thermalconductivity and the length of electron beam path lines by allowing anelectron beam generator to vary a power of the electron beam and/or varya speed at which the electron beam travels along the path lines.

An exemplary computing device comprises a memory element and aprocessing element. The memory element may be configured to store athree-dimensional model of a part to be manufactured, wherein thethree-dimensional model defines a plurality of cross sections of thepart. The processing element may be in electronic communication with thememory element. The processing element may be configured to receive thethree-dimensional model, determine a path across a surface of each crosssection, wherein the path includes a plurality of parallel lines,calculate a power for a radiation beam to scan each of the lines, suchthat the power varies non-linearly according to a length of the line,and calculate a scan speed for the radiation beam for each of the lines,such that the scan speed varies non-linearly according to the power ofthe radiation beam.

Another aspect of the invention provides an electron beam melt machinecomprising an electron beam generator and a computing device. Theelectron beam generator may be configured to generate an electron beamwhich is utilized to melt and fuse raw material to manufacture a part.The computing device may control the operation of the electron beam meltmachine and may comprise a memory element and a processing element. Thememory element may be configured to store a three-dimensional model ofthe part, wherein the three-dimensional model defines a plurality ofcross sections of the part. The processing element may be in electroniccommunication with the memory element. The processing element may beconfigured to receive the three-dimensional model, determine a pathacross a surface of each cross section, wherein the path includes aplurality of parallel lines, calculate a power for the electron beam toscan each of the lines, such that the power varies non-linearlyaccording to a length of the line, and calculate a scan speed for theelectron beam for each of the lines, such that the scan speed variesnon-linearly according to the power of the electron beam.

Yet another aspect of the invention provides a method for controllingthe operation of an electron beam melt machine. The method comprises thesteps of: receiving a three-dimensional model including data defining aplurality of cross sections of a part to be manufactured, determining apath across a surface of each cross section, the path including aplurality of parallel lines, calculating a power for an electron beam toscan each of the lines, such that the power varies non-linearlyaccording to a length of the line, and calculating a scan speed for theelectron beam for each of the lines, such that the scan speed variesnon-linearly according to the power of the electron beam.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the current invention will be apparent from thefollowing detailed description of the embodiments and the accompanyingdrawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the current invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is a schematic block diagram of components of a computing device,constructed in accordance with various embodiments of the currentinvention, in electronic communication with components of an electronbeam melt machine;

FIG. 2 is a front sectional view of the electron beam melt machine,including an electron beam generator generating an electron beam onto araw material plate which retains raw material that is melted and fusedto manufacture a part;

FIG. 3 is a front perspective view of the part along with virtual crosssections of the part;

FIG. 4 is a top view of the raw material plate in isolation, depicting alayer of raw material on which the electron beam is scanning a path ofparallel lines that melts and fuses the raw material to form a portionof one cross section of the part;

FIG. 5A is a plot of the electron beam power vs. the length of the linesof the path of FIG. 4;

FIG. 5B is a plot of the electron beam scan speed vs. the electron beampower; and

FIG. 6 is a listing of at least a portion of the steps of a method forcontrolling the operation of an electron beam melt machine.

The drawing figures do not limit the current invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following detailed description of the invention references theaccompanying drawings that illustrate specific embodiments in which theinvention can be practiced. The embodiments are intended to describeaspects of the invention in sufficient detail to enable those skilled inthe art to practice the invention. Other embodiments can be utilized andchanges can be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense. The scope of the present invention is definedonly by the appended claims, along with the full scope of equivalents towhich such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the current technology can include a variety of combinationsand/or integrations of the embodiments described herein.

A computing device 10, constructed in accordance with variousembodiments of the current invention, for controlling the operation ofadditive manufacturing machinery, such as an electron beam melt (EBM)machine 12, is shown in FIG. 1. The computing device 10 may broadlycomprise a memory element 14 and a processing element 16 which interactwith electronic components of the EBM machine 12 to control the powerand motion of a radiation beam—specifically, an electron beam 18, alsoreferred to herein as an “e beam” 18. In some embodiments, the computingdevice 10 may be integrated with, housed within, or considered part ofthe EBM machine 12. In other embodiments, the computing device 10 may bea standalone unit that is in electronic communication with the EBMmachine 12. The computing device 10 and/or the EBM machine 12 mayfurther comprise a display, a user interface such as a keyboard andmouse, a communication element to allow the device 10 and/or machine 12to communicate wirelessly or through wires with other devices orsystems, and so forth.

At least a portion of an exemplary EBM machine 12 is shown in FIG. 2utilizing the e beam 18 to create a part 20. The EBM machine 12 maycomprise a housing 22, one or more raw material hoppers 24, a rake 26, abuild tank 28, a raw material plate 30, an e beam generator 32, an ebeam power source 34, e beam deflector 36, and an e beam deflectorcircuitry 38.

The housing 22 generally stores at least a portion of the othercomponents and forms a vacuum chamber during operation of the EBMmachine 12. Exemplary embodiments of the housing 22 include four sidewalls, a top wall, and a bottom wall formed from high strength materialssuch as steel. One or more of the walls may have openings to provideaccess to other components and/or may be removable.

The raw material hopper 24 generally retains a supply of raw material tobe delivered to build tank 28. Typically, the raw material is a powderedform of one or more metals, such as aluminum, copper, gold, silver,titanium, cobalt, chrome, carbon steel, or the like, or alloys, such asaluminum 6061, aluminum 7075, titanium T6Al4V, and so forth. The rawmaterial hopper 24 may have a generally box or cylindrical shape with anopen top to receive raw material and a funneled bottom. The raw materialhopper 24 may also include a side chute with a slidable door that opensto release the raw material. The EBM machine 12 may further include alanding 40 located beside the build tank 28 onto which raw material isdeposited from the raw material hopper 24. In embodiments of the EBMmachine 12 with two raw material hoppers 24, the hoppers 24 arepositioned on opposing sides of the build tank 28.

The rake 26 generally pushes the raw material from the landing 40 underthe raw material hopper 24 into the build tank 28. The rake 26 may beelongated and have a triangular, rectangular, or square cross-sectionwith one or more edges that contact the raw material. The EBM machine 12may include actuating devices that push and/or pull the rake 26 in orderto move the raw material.

The build tank 28 generally retains the raw material in place while apart is being formed. The build tank 28 may include fourvertically-oriented walls that form a shaft through which the rawmaterial bed can slide. The build tank 28 may be positioned in thecenter of the lower half of the housing 22.

The raw material plate 30 generally retains one layer of raw materialthat is used to form a portion of the part 20. The raw material plate 30may have a thin two-dimensional shape, such as circular, oval,rectangular, square, octagonal, etc., and may be constructed from metalsor similar hardened materials. Various embodiments of the raw materialplate 30 may include a non-stick coating on an upper surface thereof.The raw material plate 30 may be positioned within the build tank 28such that the edges of the raw material plate 30 contact the sides ofthe build tank 28. In other embodiments, the raw material plate 30 mayhave a surface area that is smaller than the area of the opening of thebuild tank 28, such that there is a gap between the edges of the rawmaterial plate 30 and the sides of the build tank 28. An arm may beconnected to the bottom surface of the raw material plate 30 whichactuates the plate 30 up and down within the build tank 28.Alternatively, the bottom surface of the raw material plate 30 may beconnected to another plate which itself is actuated, so that thecombination of the plate 30 and the plate move up and down within thebuild tank 28.

The e beam generator 32 generally provides the e beam 18 and may includeknown electron beam generation and acceleration components such as ahigh-voltage filament/cathode/anode combination, lenses, coils, or othercomponents to prevent astigmatism and focus the beam, and the like. Thepower or energy of the e beam 18 may be proportional to an electriccurrent, voltage, or other electrical characteristic received by the ebeam generator 32. The e beam generator 32 may be positioned on an uppersurface of the top wall of the housing 22 and may generate the e beam 18downward through an opening in the top wall.

The e beam power source 34 generally controls the power delivered by thee beam 18 by controlling the electric current supplied to the e beamgenerator 32. The e beam power source 34 may include transformers,rectifiers, regulators, amplifiers, filters, and the like, all of whichare capable of handling large values of electric current and/or voltage.The e beam power source 34 may receive a signal, data, or combinationsthereof from the computing device 10. The signal may include a current,a voltage, a resistance, or the like which is amplified, transformed,used as a trigger, or otherwise modified to set the value of theelectric current supplied to the e beam generator 32. The data from thecomputing device 10 may provide instructions on electric current levelcontrol or a sequence of values for the electric current supplied to thee beam generator 32. In other embodiments, the e beam power source 34may alternatively or additionally control a voltage or other electricalcharacteristic or property that is supplied to the e beam generator 32.

The e beam deflector 36 generally controls the motion of the e beam 18.The e beam deflector 36 may include one or more electric coils, one ormore pairs of electric plates, or the like, or combinations thereof. Thee beam deflector 36 may be positioned along the axis or trajectory ofthe e beam 18 such that the e beam 18 passes through the coils and/orbetween the plates. The e beam deflector 36 may generate magnetic and/orelectric fields that steer or deflect the e beam 18 to follow the pathlines to melt the raw material as discussed in more detail below.

The e beam deflector circuitry 38 generally controls the operation ofthe e beam deflector 36. The e beam deflector circuitry 38 may includetransformers, rectifiers, regulators, amplifiers, filters, and the like.The e beam deflector circuitry 38 may receive a signal, data, orcombinations thereof from the computing device 10. The signal mayinclude a current, a voltage, a resistance, or the like which isamplified, transformed, used as a trigger, or otherwise modified to setof a level of electric current, voltage, or other electricalcharacteristic or property that is supplied to the e beam deflector 36.The data from the computing device 10 may provide instructions, asequence of values, or the like to set the level of electric current,voltage, or other electrical characteristic or property that is suppliedto the e beam deflector 36.

The EBM machine 12 may operate as follows. A three-dimensional computermodel of the part 20 to be manufactured is created. The model mayinclude coordinates of material boundaries 42 or surface area dimensionsfor each of a plurality of cross sections 44 of the part 20. Each crosssection 44 is a portion of the part 20 created by virtually sectioningthe part 20 into thin, parallel, planar pieces. In an XYZ coordinatesystem, the sectioning may occur along the XY, YZ, or XZ plane or atangles to any of the planes. An exemplary part 20, shown in FIG. 3, maybe a hexagonal block. Each cross section 44 is a disc whose boundaries42 form a hexagon. The model may be created by scanning an alreadyfinished part 20 and then virtually sectioning the part 20 along aconvenient plane.

Raw material may be loaded into the raw material hopper 24 and a portionof the raw material may be released onto the landing 40. The rawmaterial plate 30 may be positioned in the build tank 28 at a depth ofone cross section 44 thickness. The rake 26 may push raw material intothe raw material plate 30 such that the raw material is evenlydistributed thereon. FIG. 4 shows the raw material plate 30 holding alayer of raw material. The e beam generator 32 may generate the e beam18 onto the raw material. The computing device 10 may provide input tothe e beam power source 34 and the e beam deflector circuitry 38 tocontrol the power and the motion of the e beam 18, as described in moredetail below. The e beam 18 is guided to scan or follow a path 46, whichmay be determined after the computer model for the part 20 is created.The path 46 may include a plurality of spaced-apart parallel lines 48that follow a serpentine pattern. Typically, the path 46 begins at oneedge or side of the boundary 42 for the current cross section 44,zig-zags back and forth across the surface, and ends at an opposing edgeor side of the boundary 42. FIG. 4 shows the boundary 42 of theexemplary part 20 and illustrates the process of the e beam 18 followingthe path 46 during the formation of the current cross section 44.Although only a portion of the path 46 is shown in FIG. 4, the remainderof the path 46 includes the same serpentine pattern that zig-zagsbetween edges of the boundary 42. FIG. 4 also shows a melt pool 50,which is the region around the e beam 18 spot where the raw material ismelted. As the melted material cools, it fuses to form the cross section44. Once the e beam 18 has been guided to scan the entire path 46, the ebeam 18 is turned off.

The raw material plate 30 may be lowered in the build tank 28 by adistance equal to one cross-sectional thickness. The raw material hopper24 may release more raw material, or there may be sufficient rawmaterial left on the landing 40. In either case, the rake 26 may move asecond layer of raw material into the raw material plate 30 to be placedon top of the first layer of unmelted raw material and the first crosssection 44. The e beam generator 32 may generate the e beam 18 onto theraw material and may be guided to scan the path 46. If the second crosssection 44 has the same shape as the first cross section 44, then thepath 46 may be the same. If any of the cross sections 44 has a differentshape than any of the others (such as from the boundary 42 of the crosssection 44 being different), then there is a unique path 46 for eachcross section 44 that has a different shape. And, although the path 46may be different for differently shaped cross sections 44, the path 46still follows the same serpentine pattern starting at one edge of theboundary 42 and ending at the opposite edge of the boundary 42. Once thee beam 18 has been guided along the entire path 46 for the second crosssection 44, the e beam 18 is turned off. The raw material plate 30 islowered in the build tank 28 by another cross-sectional thickness andanother layer of raw material is placed on top of previous layers of rawmaterial and previously-formed cross sections 44. The e beam 18 isguided along the path 46 to melt and form another cross section 44. Theprocess of adding raw material and forming cross sections 44, asdescribed above, continues all of the cross sections 44 have beenformed. Excess raw material may be stuck to the cross sections 44. Theexcess raw material may be removed with pressurized air, brushing, andthe like—after which, the part 20 is complete.

Focusing now on the computing device 10 that provides control of theoperation of the EBM machine 12, the memory element 14 may includeelectronic hardware data storage components such as read-only memory(ROM), programmable ROM, erasable programmable ROM, random-access memory(RAM) such as static RAM (SRAM) or dynamic RAM (DRAM), cache memory,hard disks, floppy disks, optical disks, flash memory, thumb drives,universal serial bus (USB) drives, or the like, or combinations thereof.In some embodiments, the memory element 14 may be embedded in, orpackaged in the same package as, the processing element 16. The memoryelement 14 may include, or may constitute, a “computer-readable medium”.The memory element 14 may store the instructions, code, code segments,software, firmware, programs, applications, apps, services, daemons, orthe like that are executed by the processing element 16. The memoryelement 14 may also store settings, data, documents, sound files,photographs, movies, images, databases, and the like.

The processing element 16 may include electronic hardware componentssuch as processors, microprocessors (single-core and multi-core),microcontrollers, digital signal processors (DSPs), field-programmablegate arrays (FPGAs), analog and/or digital application-specificintegrated circuits (ASICs), or the like, or combinations thereof. Theprocessing element 16 may generally execute, process, or runinstructions, code, code segments, software, firmware, programs,applications, apps, processes, services, daemons, or the like. Theprocessing element 16 may also include hardware components such asfinite-state machines, sequential and combinational logic, and otherelectronic circuits that can perform the functions necessary for theoperation of the current invention. Furthermore, the processing element16 may include electronic circuitry such as digital to analogconverters, amplifiers, and so forth. The processing element 16 may bein communication with the other electronic components through serial orparallel links that include universal busses, address busses, databusses, control lines, and the like.

The processing element 16 may be configured or programmed, throughhardware, firmware, software, or combinations thereof, to perform thefollowing functions for controlling the operation of additivemanufacturing machinery. The processing element 16 may receive, from anexternal device, machine, or system, the three-dimensional model of thepart 20 to be created. The model may be stored in the memory element 14.The model may include surface area dimensions, coordinates ofboundaries, and/or similar data that define each of the cross sections44 of the part 20. From this data, the processing element 16 maygenerate the path 46 for each cross section 44. As best illustrated inFIG. 4, the path 46 includes a plurality of spaced-apart, parallel lines48 that extend from one edge of the boundary 42 to another edge of theboundary 42.

Once the path 46 for each cross section 44 is generated, the processingelement 16 may determine the power of the e beam 18 and the speed withwhich the e beam scans or travels along each line 48. The e beam powerand the e beam scan speed as the e beam 18 is guided, deflected, orsteered to scan any given line 48 of the path 46 are generally constantfor the entire length of the line 48, although, in some embodiments, thee beam power and the e beam scan speed may each be varied while the ebeam 18 is scanning a line 48. However, the values of the e beam powerand the e beam scan speed may be determined based on, or may varyaccording to, the length of the line 48. In general, there is anon-linear relationship between the length of the line 48 and the valuesof the e beam power and the e beam scan speed for that particular line48. Specifically, as illustrated in the plot of e beam power vs. linelength shown in FIG. 5A, the e beam power increases non-linearly withrespect to the length of the line 48. The non-linear relationshipbetween the length of the line 48 and the value of the e beam power maybe expressed by equations that include exponential functions,logarithmic functions, polynomial functions, sinusoidal functions, etc.As illustrated in FIG. 5B, the e beam scan speed increases non-linearlywith respect to the e beam power. Likewise, as above, the non-linearrelationship between the e beam power and the value of the e beam scanspeed may be expressed by equations that include exponential functions,logarithmic functions, polynomial functions, sinusoidal functions, etc.Thus, the processing element 16 increases the power of the e beam 18exponentially, as an example, for an increase in the length of the line48. And, the processing element 16 increases the scan speed of the ebeam 18 exponentially, as an example, with an increase in the power ofthe e beam 18.

Furthermore, the processing element 16 may take into account the thermalproperties, such as thermal conductivity, of the raw material used tomanufacture the part 20 when calculating the e beam power and the e beamscan speed. In general, the values of e beam power and scan speed may begreater for a material with a higher thermal conductivity than a lowerthermal conductivity material for a line of the same length. This helpsto ensure that the higher thermal conductivity material does not cooltoo much during the scanning process. Thermal conductivity may beincluded in equations to calculate e beam power and scan speed as avariable scaling factor, a variable additive term, or the like.

In some embodiments, the processing element 16 may calculate the valuesof the e beam power and the e beam scan speed for each line 48 of eachcross section 44 using equations mentioned above. The calculations maybe performed for all of the lines 48 and stored in the memory element 14before the e beam scanning process to form the part 20 begins.Alternatively, the calculation of the values of the e beam power and thee beam scan speed for each line 48 may be performed as needed, such asbefore each line 48 is scanned during the process of forming the part20. In other embodiments, the values of the e beam power and the e beamscan speed for lines 48 of a plurality of lengths may be stored as atable in the memory element 14. For example, the values of the e beampower and the e beam scan speed for lines 48 ranging in length from 0meters (m) to 2 m in 0.1 millimeter (mm) resolution may be stored in thememory element 14. Once the processing element 16 determines the lengthof each line 48, it may access the memory element 14 and look up thevalues of the e beam power and the e beam scan speed for the line lengththat is closest in value to the currently-determined length of the line48.

Once the path 46 for each cross section 44 has been determined and thevalues of the e beam power and the e beam scan speed for each line 48have either been calculated or are ready to be accessed, the processingelement 16 may initiate the scanning and melting process that forms thepart 20. The processing element 16 may communicate with the e beam powersource 34 and the e beam deflector circuitry 38 to generate the e beam18 with a certain power and to deflect, guide, steer, or move the e beam18 to scan the path 46 with a certain scan speed. In some embodiments,the processing element 16 may transmit a first signal to the e beampower source 34, wherein the first signal includes an electricalcharacteristic, such as an electric current, a voltage, a resistance,etc., which is varied according to the value of the e beam power for thecurrently-scanned line 48. For example, the first signal having agreater electric current may correspond to a greater e beam power. Inother embodiments, the processing element 16 may transmit data to the ebeam power source 34 which includes instructions, a sequence of values,or the like that sets the level of the e beam power for thecurrently-scanned line 48. Likewise with the scan speed, the processingelement 16 may transmit a second signal to the e beam deflectorcircuitry 38, wherein the second signal includes an electricalcharacteristic, such as an electric current, a voltage, a resistance,etc., which is varied according to the value of the e beam scan speedfor the currently-scanned line 48. For example, the second signal havinga greater electric current may correspond to a greater e beam scanspeed. In other embodiments, the processing element 16 may transmit datato the e beam deflector circuitry 38 which includes instructions, asequence of values, or the like that sets the level of the e beam scanspeed for the currently-scanned line 48. The processing element 16 mayalso transmit a third signal or data to the e beam deflection circuitry38 that provide the direction in which to guide, deflect, steer, or movethe e beam 18 to scan the path 46.

The processing element 16 may continue to transmit signals and/or datathe e beam power source 34 and the e beam deflector circuitry 38 thatset values or levels for the e beam power, the e beam scan speed, andthe e beam 18 direction for each line 48. The transmission may occurbefore each line 48 is scanned. In alternative embodiments, the e beampower source 34 and the e beam deflector circuitry 38 may include datastorage components capable of storing a sequence of values. In suchembodiments, the processing element 16 may transmit the data to the ebeam power source 34 and the e beam deflector circuitry 38 for the ebeam power, the e beam scan speed, and the e beam 18 direction for allthe lines 48 of the path 46 before the scan and melt process begins. Inaddition, the processing element 16 may communicate with and providecontrol of components such as the raw material hopper 24, the rake 26,and the raw material plate 30. Thus, the processing element 16 maytransmit signals and/or data to those components to set the height ofthe raw material plate 30, release raw material, and spread it on to theraw material plate 30 before each cross section 44 is formed. When allof the cross sections 44 have been formed, the processing element 16 maytransmit an alert, such as activating a light, sounding an alarm, orsending a message, that the part 20 is complete.

Another aspect of the invention may provide a method 100 for controllingthe operation of additive manufacturing machinery, such as an electronbeam melt (EBM) machine 12. The EBM machine 12 may utilize an electronbeam (“e beam”) 18 to melt and fuse raw material in an additivemanufacturing process to create a part 20. At least a portion of thesteps of the method 100 are shown in FIG. 6. The steps may be performedin the order shown in FIG. 6, or they may be performed in a differentorder. Furthermore, some steps may be performed concurrently as opposedto sequentially. In addition, some steps may be optional. The steps maybe performed by a processing element 16 of a computing device 10.

Referring to step 101, a three-dimensional model is received, the modelincluding data defining a plurality of cross sections 44 of the part 20to be manufactured. The model may include surface area dimensions,coordinates of boundaries 42, and/or similar data that define each ofthe cross sections 44 of the part 20. Each cross section 44 may be aportion of the part 20 created by virtually sectioning the part 20 intothin, parallel, planar pieces. In an XYZ coordinate system, thesectioning may occur along the XY, YZ, or XZ plane or at angles to anyof the planes. An exemplary part 20, shown in FIG. 3, may be a hexagonalblock. Each cross section 44 is a disc whose boundaries 42 form ahexagon. The model may be created by an external device, machine, orsystem which scans an already finished part 20 and then virtuallysections the part 20 along a convenient plane.

Referring to step 102, a path 46 across a surface of each cross section44 is determined. The path 46 may include a plurality of spaced-apartparallel lines 48 that follow a serpentine pattern. Typically, the path46 begins at one edge or side of the boundary 42 for the current crosssection 44, zig-zags back and forth across the surface, and ends at anopposing edge or side of the boundary 42. FIG. 4 shows the boundary 42of the exemplary part 20 and illustrates the process of the e beam 18following the path 46 during the formation of the current cross section44. Although only a portion of the path 46 is shown in FIG. 4, theremainder of the path 46 includes the same serpentine pattern thatzig-zags between edges of the boundary 42.

Referring to step 103, a power for the e beam 18 to scan each of thelines 48 is calculated. In general, there is a non-linear relationshipbetween the length of the line 48 and the value of the e beam power forthat particular line 48. Specifically, as illustrated in the plot of ebeam power vs. line length shown in FIG. 5A, the e beam power increasesnon-linearly with respect to the length of the line 48. The non-linearrelationship between the length of the line 48 and the value of the ebeam power may be expressed by equations that include exponentialfunctions, logarithmic functions, polynomial functions, etc. Thus, forlonger lines 48, the processing element 16 increases the power of the ebeam 18 exponentially, as an example.

Referring to step 104, a scan speed for the e beam 18 for each of thelines 48 is calculated. In general, there is a non-linear relationshipbetween the length of the line 48 and the value of the e beam scan speedfor that particular line 48. As illustrated in FIG. 5B, the e beam scanspeed increases non-linearly with respect to the e beam power. Likewise,as above, the non-linear relationship between the e beam power and thevalue of the e beam scan speed may be expressed by equations thatinclude exponential functions, logarithmic functions, polynomialfunctions, etc. When the e beam 18 is generated at higher power forlonger lines 48, the processing element 16 increases the scan speed ofthe e beam 18 exponentially, as an example.

In some embodiments, the processing element 16 may calculate the valuesof the e beam power and the e beam scan speed for each line 48 of eachcross section 44 using equations mentioned above. The calculations maybe performed for all of the lines 48 and stored in the memory element 14before the e beam scanning process to form the part 20 begins.Alternatively, the calculation of the values of the e beam power and thee beam scan speed for each line 48 may be performed as needed, such asbefore each line 48 is scanned during the process of forming the part20. In other embodiments, the values of the e beam power and the e beamscan speed for lines 48 of a plurality of lengths may be stored as atable in the memory element 14. For example, the values of the e beampower and the e beam scan speed for lines 48 ranging in length from 0meters (m) to 2 m in 0.1 millimeter (mm) resolution may be stored in thememory element 14. Once the processing element 16 determines the lengthof each line 48, it may access the memory element 14 and look up thevalues of the e beam power and the e beam scan speed for the line lengththat is closest in value to the currently-determined length of the line48.

Referring to step 105, the e beam power and the e beam scan speed foreach line 48 of the path 46 for each cross section 44 is communicated toan additive manufacturing machine. In some embodiments, the processingelement 16 may transmit a first signal to the e beam power source 34,wherein the first signal includes an electrical characteristic, such asan electric current, a voltage, a resistance, etc., which is variedaccording to the value of the e beam power for the currently-scannedline 48. For example, the first signal having a greater electric currentmay correspond to a greater e beam power. Additionally or alternatively,the processing element 16 may transmit data to the e beam power source34 which includes instructions, a sequence of values, or the like thatsets the level of the e beam power for the currently-scanned line 48.Likewise with the scan speed, the processing element 16 may transmit asecond signal to the e beam deflector circuitry 38, wherein the secondsignal includes an electrical characteristic, such as an electriccurrent, a voltage, a resistance, etc., which is varied according to thevalue of the e beam scan speed for the currently-scanned line 48. Forexample, the second signal having a greater electric current maycorrespond to a greater e beam scan speed. Additionally oralternatively, the processing element 16 may transmit data to the e beamdeflector circuitry 38 which includes instructions, a sequence ofvalues, or the like that sets the level of the e beam scan speed for thecurrently-scanned line 48. The processing element 16 may also transmit athird signal and/or data to the e beam deflection circuitry 38 thatprovide the direction in which to guide, deflect, steer, or move the ebeam 18 to scan the path 46.

The concepts and principles of the current invention apply generally toother radiation beam melt technologies. For example, selective lasermelt machines operate on similar principles to the EBM machine 12. Theselective laser melt machine includes a radiation beam generator, i.e.,a laser, to generate a radiation beam, i.e., a laser beam, which isdeflected or guided to scan a path, thereby melting and fusing rawmaterial in order to manufacture a part. The selective laser meltmachine may further include a power source for the laser along withelectronic circuitry to set the level of laser power and laser beamdeflection components, such as mirrors, splitters, and/or lenses, alongwith electronic circuitry to position the components. Thus, thecomputing device 10 of the current invention may interact with theselective laser melt machine in a similar manner to the EBM machine 12.For example, the three-dimensional model of the part 20 would be thesame, so the processing element 16 may determine the path 46 for eachcross section 44 in the same manner. Although the values of power forthe laser beam may be different from the values of power for the e beam18, the processing element 16 may calculate the power for the laser beamin the same manner. Hence, the laser beam power may vary non-linearlyaccording to the lengths of the lines of the paths for each crosssection. The processing element 16 may increase the laser beam powerexponentially, as an example, for an increase in the length of the line.In addition, the processing element 16 may calculate the scan speed forthe laser beam in the same manner as for the e beam 18. Hence, the laserbeam scan speed may vary non-linearly according to the laser beam powerfor a given line. The processing element 16 may increase the laser beamscan speed exponentially, as an example, for an increase in the laserbeam power. Furthermore, the values of the laser beam power and thelaser beam scan speed for each line of a path may be communicated to theselective laser melt machine in a similar manner.

Although the invention has been described with reference to theembodiments illustrated in the attached drawing figures, it is notedthat equivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described various embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:
 1. A computing device for controlling the operation of anadditive manufacturing machine, the computing device comprising: amemory element configured to store a three-dimensional model of a partto be manufactured, the three-dimensional model defining a plurality ofcross sections of the part; and a processing element in electroniccommunication with the memory element, the processing element configuredto receive the three-dimensional model, determine a path across asurface of each cross section, the path including a plurality ofparallel lines, calculate a power for a radiation beam to scan each ofthe lines, such that the power varies non-linearly according to a lengthof the line for each line, calculate a scan speed for the radiation beamfor each of the lines, such that the scan speed varies non-linearlyaccording to the power of the radiation beam for each line, generate afirst signal to be received by a first component that controls powerdelivered by the radiation beam, control the power delivered to theradiation beam based on the first signal, the first signal including anelectrical characteristic or data that varies according to eachdetermined radiation beam power, and generate a second signal to bereceived by a second component that controls a motion of the radiationbeam, control the motion of the radiation beam based on the secondsignal, the second signal including an electrical characteristic or datathat varies according to each determined radiation beam scan speed. 2.The computing device of claim 1, wherein the processing element isfurther configured to communicate the radiation beam power and theradiation beam scan speed for each line of the path for each crosssection to the additive manufacturing machine.
 3. The computing deviceof claim 1, wherein the power for the radiation beam to scan one linecalculated by the processing element is constant for the entire lengthof the line.
 4. The computing device of claim 1, wherein the scan speedfor the radiation beam to scan one line calculated by the processingelement is constant for the entire length of the line.
 5. The computingdevice of claim 1, wherein the processing element calculates the powerfor the radiation beam to scan each of the lines, such that the powerincreases logarithmically with an increase in the length of the line. 6.The computing device of claim 1, wherein the processing elementcalculates the scan speed for the radiation beam to scan each of thelines, such that the scan speed increases logarithmically with anincrease in the power for the radiation beam.
 7. The computing device ofclaim 1, wherein the processing element calculates the power and scanspeed for an electron beam to scan each of the lines.
 8. The computingdevice of claim 1, wherein the processing element calculates the powerand scan speed for a laser beam to scan each of the lines.
 9. Anelectron beam melt machine comprising: an electron beam generatorconfigured to generate an electron beam utilized to melt and fuse rawmaterial to manufacture a part; and a computing device for controllingthe operation of the electron beam melt machine, the computing devicecomprising a memory element configured to store a three-dimensionalmodel of the part, the three-dimensional model defining a plurality ofcross sections of the part, and a processing element in electroniccommunication with the memory element, the processing element configuredto receive the three-dimensional model, determine a path across asurface of each cross section, the path including a plurality ofparallel lines, calculate a power for a electron beam to scan each ofthe lines, such that the power varies non-linearly according to a lengthof the line for each line, calculate a scan speed for the electron beamfor each of the lines, such that the scan speed varies non-linearlyaccording to the power of the electron beam for each line, generate afirst signal to be received by a first component that controls powerdelivered by the radiation beam, control the power delivered to theradiation beam based on the first signal, the first signal including anelectrical characteristic or data that varies according to eachdetermined radiation beam power, and generate a second signal to bereceived by a second component that controls a motion of the radiationbeam, control the motion of the radiation beam based on the secondsignal, the second signal including an electrical characteristic or datathat varies according to each determined radiation beam scan speed. 10.The electron beam melt machine of claim 9, wherein the processingelement is further configured to communicate the electron beam power andthe electron beam scan speed for each line of the path for each crosssection to the electron beam melt machine.
 11. The electron beam meltmachine of claim 9, wherein the power for the electron beam to scan oneline calculated by the processing element is constant for the entirelength of the line.
 12. The electron beam melt machine of claim 9,wherein the scan speed for the electron beam to scan one line calculatedby the processing element is constant for the entire length of the line.13. The electron beam melt machine of claim 9, wherein the processingelement calculates the power for the electron beam to scan each of thelines, such that the power increases logarithmically with an increase inthe length of the line.
 14. The electron beam melt machine of claim 9,wherein the processing element calculates the scan speed for theelectron beam to scan each of the lines, such that the scan speedincreases logarithmically with an increase in the power for the electronbeam.
 15. A method for controlling the operation of an electron beammelt machine, the method comprising the steps of: receiving athree-dimensional model including data defining a plurality of crosssections of a part to be manufactured; determining a path across asurface of each cross section, the path including a plurality ofparallel lines; calculating a power for an electron beam to scan each ofthe lines, such that the power varies non-linearly according to a lengthof the line for each line; calculating a scan speed for the electronbeam for each of the lines, such that the scan speed varies non-linearlyaccording to the power of the electron beam for each line; generating afirst signal to be received by a first component that controls powerdelivered by the radiation beam, controlling the power delivered to theradiation beam based on the first signal, the first signal including anelectrical characteristic or data that varies according to eachdetermined radiation beam power; and generating a second signal to bereceived by a second component that controls a motion of the radiationbeam, controlling the motion of the radiation beam based on the secondsignal, the second signal including an electrical characteristic or datathat varies according to each determined radiation beam scan speed. 16.The method of claim 15, further comprising communicating the electronbeam power and the electron beam scan speed for each line of the pathfor each cross section to the electron beam melt machine.
 17. The methodof claim 15, wherein the power for the electron beam to scan one linecalculated by the processing element is constant for the entire lengthof the line.
 18. The method of claim 15, wherein the scan speed for theelectron beam to scan one line calculated by the processing element isconstant for the entire length of the line.
 19. The method of claim 15,wherein the processing element calculates the power for the electronbeam to scan each of the lines, such that the power increaseslogarithmically with an increase in the length of the line.
 20. Themethod of claim 15, wherein the processing element calculates the scanspeed for the electron beam to scan each of the lines, such that thescan speed increases logarithmically with an increase in the power forthe electron beam.